Figure 1.

(A) Schematic illustration for L-Trp dependent regulation of the tnaCAB operon in E. coli. (B) Schematic illustration of the construct used to purify TnaC–RNCs. A reporter expressing the cleavable His₈-3C-Titin-I27-TnaC stalling peptide from a pBAD plasmid was used in a E. coli KC6 ΔsmpB ΔssrA strain (25) and RNCs were purified as described in Materials and Methods. (C) Cryo-EM maps of the TnaC-stalled 70S-RNA, without (left panel) and with bound RF2 and ArfA. The peptide exit tunnel (PET) is outlined with a dashed line (yellow).